It is desirable to reduce wave-making characteristics in the hulls of water vessels, such as full displacement hulls. The vessels which can benefit from the design arrangements specified here include those which operate at speeds where wave-making can prove to be significant, usually at speeds where the ratio of speed in knots to the square root of the vessel length is in the range of 0.20 and above.
Traditional approaches to hull design are based upon classic hull forms typified by studies of a series of hulls, such as the Taylor Series and Series 60. These Series utilize hull configurations that vary section areas as decreasing segments as the section increases in depth. Such that in the bow and stern sections, the forms are of decreasing width as the section increases in depth below the waterline. This traditional approach creates compound curvatures in hull plate surfaces and simplex curvature in hull frame sections.
The non-traditional approach to hull design and performance proposed in the parent of this application, i.e., application Ser. No. 09/979,595 of Reynolds, avoids expensive plate and hull shapes. Although the '595 application focused on semi-displacement hulls (i.e., hulls where at least some planing is present), certain concepts of the non-traditional approach may be applied to full displacement hulls. In this non-traditional approach, hull sections are developed as straight, with hard chines that develop bottom deadrise. Wave-making reduction is developed longitudinally rather than vertically (as in the traditional Series forms). This means that hull separation of the lo incident water stream is accomplished by extending the entrance (or bow form), where the parallel midbody is non-existent, rather than decreasing separation potential energies as depth increases.
The concept of a parallel midbody is a traditional approach for minimizing hull form variations and optimizing construction costs. Non-traditional hull design eliminates the parallel midbody and minimizes station configuration. This minimization results in straight sides, and does not create compound curves for the side shell. Non-traditional straight transverse sided sections reduce or eliminate compound curvature. Non-traditional straight sided transverse sections, as presented herein, create midbody plate panels that are essentially straight (e.g., infinite radius of curvature) but may not be parallel to the centerline. The midbody may be more trapezoidal than rectangular.
The present invention teaches that low wave-making can be defined by waterline sections. By dividing the length of the hull into substantially equally spaced intervals, called sections, the beam, or offset, at the waterline of each section can be specified. The principal waterline section is the water surface where wave-making energies are the highest. This is the free surface waterline, or the water surface. Wave-making extends below the water surface, but the greatest energies which react against the hull to impede motion are encountered at the water surface. The waterline profile at the water surface can be represented by a series that describes the second order difference of the station offsets.
The waterline profile can be divided into entrance offsets (bow) and run offsets (stern). Bow and stern offsets can be treated as discrete. Even though a vessel's overall efficiency depends upon the combined effects of bow and stern, they are not dependent upon each other to create separation and closing effects.
Thus, it is desirable to provide a vessel design and configuration that relies upon non-traditional approaches to reduce wave-making drag in a full displacement hull, and it is to this end that the present invention is directed.